Constraining changes in the middle Atmosphere Brewer-Dobson circulation from observations (BDCHANGE): A project in the frame of the ROMIC (Role of the Middle Atmosphere in Climate)

A joint project by Goethe University Frankfurt (Prof. Andreas Engel, Dr. Harald Bönisch) and Karlsruhe Institute of Technology (KIT) (Dr. Gabriele Stiller)

Mean age of air is the average time it takes the atmosphere to transport air from the troposphere to a given location in the stratosphere. The aim of this project is to obtain a data set in which the mean age from different sources can be combined. We will use this data set to study the long term evolution of mean age which can be used as a proxy for the strength of the Brewer-Dobson Circulation (BDC). We will combine and extend the two best data sets available worldwide of stratospheric SF6 (which is used to calculate mean age) into the future - the balloon data set by GUF (Engel et al., 2009) by a balloon flight from Southern Canada (planned in 2014 or 2015) and the satellite data set by KIT (Stiller et al., 2012). We will continuously improve the data evaluation and merge the two data sets with other satellite data sets, in particular the ACE data. We will further include a validation of the new innovative AIRCORE system (Link: (Karion et al., 2010) which may allow for more regular stratospheric in-situ observations of age tracers in the future.

The combination of these different data approaches, together with continuous work on the improvement of the way that mean age is calculated (see cooperation with TRIP proposal by FZ Jülich) will eventually improve the understanding of possible changes in the upper branch of the Brewer-Dobson circulation. 


Engel, A., Mobius, T., Bönisch, H., Schmidt, U., Heinz, R., Levin, I., Atlas, E., Aoki, S.,Nakazawa, T., Sugawara, S., Moore, F., Hurst, D., Elkins, J., Schauffler, S., Andrews, A.,and Boering, K.: Age of stratospheric air unchanged within uncertainties over the past 30 years, Nature Geoscience, 2, 28-31, doi: 10.1038/Ngeo388, 2009.

Karion, A., Sweeney, C., Tans, P., and Newberger, T., AirCore: An Innovative Atmospheric Sampling System, Journal of Atmospheric and Oceanic Technology, Nov. 2010, doi: 10.1175/2010JTECHA1448.1.

Stiller, G. P., von Clarmann, T., Haenel, F., Funke, B., Glatthor, N., Grabowski, U., Kellmann, S., Kiefer, M., Linden, A., Lossow, S., and López-Puertas, M.: Observed temporal evolution of global mean age of stratospheric air for the 2002 to 2010 period, Atmos. Chem. Phys., 12, 3311-3331, doi:10.5194/acp-12-3311-2012, 2012.